Twist lock units

ABSTRACT

A TWIST LOCK FOR USE ON A LOAD LIFTING DEVICE FOR CONNECTING THE LIFTING DEVICE TO AN APERTURED FITTING ON A LOAD, THIS UNIT HAVING A BODY, A TWIST LOCK ELEMENT ROTATABLE IN THE BODY, A TAPERED LOCK HEAD AT ONE END OF THE ELEMENT FOR ENGAGEMENT IN THE APERTURE IN THE FITTING AND ON ROTATION FOR ENGAGEMENT BENEATH THE UNDERSIDE OF A PART OF THE FITTING. THE OTHER END OF THIS ELEMENT HAS A PORTION SHAPED FOR CONNECTION TO AN ACTUATING RAM ROD FOR ROTATING THE ELEMENT INTO AND OUT OF THE LOCKING POSITION.

Jan. 5, 1971 G. N, B. SHAW 3,551,954

, TWIST LOCK UNITS Filed June 5, 1968 v 2 Sheets-Sheet 1 Hill Inventor Jan. 5, 1971 s. N. B. SHAW 3,551,964

TWIST LOCK UNITS Filed June 5, 1968 2 Sheets-Sheet 2 United States Patent O 3,551,964 TWIST LOCK UNITS George Neville Bowman Shaw, Toddington, England, assignor to Lancer Boss Limited, Leighton Buzzard, Bedfordshire, England, a corporation of Great Britain Filed June 5, 1968, Ser. No. 734,761 Claims priority, application Great Britain, Feb. 1, 1968, 5,200/ 68 Int. Cl. A44b 21/00 U.S. Cl. 24-221 6 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to twist lock units and more particularly to such units for securing a lock body to a separate part. In the lifting of heavy loads, e.g., several tons such as railway goods containers, lifting vehicles of the fork lift truck type are sometimes employed so that the fork carriages are used to engage hooks or like means on the load for raising and lowering it. Conventional railway containers have at their top corners fittings with apertures therein for engagement by hooks or other lifting means. Where cables are used suspending from a crane hook, the cables must be connected to a rigid frame so that its corners have the lifting hooks and thus only a vertical lifting force is applied to the top corners of the containers.

(2) Description of the prior art In our copending application Ser. No. 756,570, filed Aug. 30, 1968, we have described an attachment, for use with a fork lift truck which may be a side loader, with looking devices engageable one in each corner of the top of the load, e.g., a railway container to enter recesses in the load corner fittings and be engaged therein for raising the load. The locking device can be operated hydraulically from the vehicle in a conventional manner using a ram, the piston of which actuates the locking mechanism.

The main object of the present invention is to provide a twist lock unit for securing a lock body such as is connected to a fork lift truck lifting attachment, to a separate part such as the top corner fitting of a load to be lifted.

SUMMARY According to the present invention a twist lock unit for securing a lock body to a separate part e.g., a load corner fitting comprises a lock body, a twist lock assembly including a projecting shank and an element rotatably mounted in the body and supporting a lock head beyond said shank and by an actuating device to be connected thereto, the lock head being tapered for engagement in an aperture in the top of the fitting and when rotated within the fitting has a portion projecting laterally from the shank so as to be engageable beneath the under side of the fitting aperture, the shank of the as- Patented Jan. 5, 1971 sembly lying in the fitting aperture in use having a diameter equal to the narrowest width of the head whereby the shank will not foul the aperture while coupling and uncoupling the lock head to the load.

In a preferred construction the twist lock element is rotatably mounted in the body and supports the lock head at one end thereof while its other end has an axially cut away portion, and a pin disposed in a boring in the element extends parallel to the longitudinal axis of the element, the pin providing a gudgeon pin for engagement by an actuating rod or the like, the arrangements being such that longitudinal displacement of the rod or the ilke transversely of the pin will cause the element to rotate in the body to bring one or more portions of the lock head into a position where it engages the under side of the comer fitting aperture to lock the unit thereto.

Preferably the element comprises a cylindrical part rotatably mounted in a bearing in the body which projects from the body to form the shank of the assembly, the bearing extending down the element to its head and having a diameter equal in cross section to the smallest dimension of the upper part of the head. The shank is preferably a split bearing surrounding the cylindrical part of the element. A medial section of the element is cut away to present axially spaced collars and the medial section extending parallel to and spaced from the longitudinal axis of the element, the collars, having aligned bores to receive the pin for connecting the rod or the like with the pin axis parallel but offset from the longitudinal axis of the element, whereby longitudinal movement of the rod or the like transversely of the axis of the element will cause the element to rotate through part of a circle about its axis in the body.

The element preferably at its upper end has a portion of reduced cross section which when rotated may engage a contact or one of spaced contacts in an electric circuit with a switch which is actuated by the element in either its locking and unlocking positions.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may me more fully understood an embodiment in accordance therewith will now be described by way of example with reference to the accompanying drawings, in which:

FIG. 1 is a vertical cross section through the twist lock unit;

FIG. 2 is a side elevation of the twist lock element;

FIG. 3 is a view similar to FIG. 2 at right angles thereto;

FIG. 4 is a cross section on the line IVIV of FIG. 1;

FIG. 5 is a cross section on the line VV of FIG. 1; and

FIG. 6 is a cross section on the line VI-VI of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, this shows part of a standard top corner of a fitting of a freight, e.g., railway freight container 1 in which there is a recess 2 having an aperture 3 in the top shaped to enable the lock head 4 shown in side elevation to be described to enter when in the position shown in FIG. 1 but which can be rotated at right angles thereto when the portion '5 at its upper end engages under the edges of the aperture 3 as in dotted lines in FIG. 1, so that when the lock body is raised as by the attachment on a fork lift truck carriage, the load will be lifted by a vertical force on each of its four corners.

The twist lock unit comprises a body 6 having a bore 7 therein lined by a split bearing 8 which depends from the body and forms a shank of a twist lock assembly 3 in which a cylindrical part 9 of a twist lock element is rotatably mounted. The outer diameter of this hearing 8 is the same throughout its length as the smallest cross sectional dimension (X in FIG. 4) of the head 5.

The body has a central aperture 10 with a side opening 11 and above the portion 10 there is a bearing 12 in which is rotatably secured a collar 13 of the twist lock element.

The collar 13 is connected to a further collar 14 integral with the cylindrical portion 9 through a medial section 15 "which, as seen in FIG. 5, forms a chord of the circle of the plan of the collar 14. Extending through the resultant gap 16 in the medial section 15 is a gudgeon 17 journalled in bearings 18 in the collars 13, 14. The pin 17 is secured by a C-ring 19 in the upper bearing 18 and has a bearing 20 round it in the gap 16. Mounted on the bearing is a rod 21 having a portion 22 for connection to an operating thrust rod not shown, such as the piston rod of an hydraulic ram which can be actuated from the vehicle.

The pin 17 as seen in FIG. 5 and indicated in dotted lines in FIGS. 2 and 3 is eccentrically mounted of the vertical axis of the medial section 15 so that when the rod 21 is moved to the left in FIG. 1 the twist lock element will be caused to rotate through a suitable angle such as 90, and thereby the portion 5 of the lock head 4 is brought into the locking position below the aperture in the top of the load corner fitting.

The shank of the twist lock assembly is formed by the depending portion of the bearing 8, so that as seen in FIG. 4, the element in the unlocking position cannot foul the opening in the fitting because there is no part of the twist lock assembly projecting as in existing devices to foul the edge of the aperture.

Above the collar 13 there is in an integral portion of the element shown as a contact portion 23 which as seen in FIG. 5 is a 90 secant of a circle cut away at the centre part 26 providing a clearance from the pin 17 and the bearing 18. On either side of the central transverse axis Y of the part 23 there is a contact of a microswitch 24 which controls a fluid circuit and acts as a warning device as well as a stop to further rotation of the element. Each microswitch 24 forms part of a locking device supplied with fluid under pressure through ducts 25 so that when the unit is in the locking or unlocking position, one or other of the microswitches 24 prevents further rotation of the portion 23, and when the element 15 is moved to the locked or unlocked position the switch 24 initiates a signal giving warning that the attachment is locked to or can be uncoupled from the load. In an intermediate position neither switch 24 is actuated and thus the attachment cannot be operated thus avoiding any damage to the corner fitting or to the lock unit.

It will be seen that by means of this arrangement a firm and secure positive acting lock is provided which will provide an adequate hold from above of the load and cannot foul the corner fitting. The shank of the twist lock assembly is made such that it will pass with minimum tolerance through the aperture 3 in the container top and thus when the unit is in the locking position there can be no substantial play in the horizontal direction which could cause the unit to jam on the load.

Iclaim:

1. A twist lock unit adapted to be securely carried by a load container lifting device for securing the device 4 to a load corner fitting on a container, such fitting having an elongate aperture therein; said lock unit comprising a lock body secured to and carried by the lifting device, a twist lock assembly including a shank depending from said body and an element rotatably mounted in the body and presenting a lock head at the lower end of said shank and an actuating device coupled to the element and extending at right angles thereto'for rotating said element to move said lock head between locking and unlocking positions, said lock head being tapered for engagement in the aperture in the top of the fitting and having a portion at its upper part projecting laterally of the shank when rotated within the fitting so as to be engageable beneath the underside of the fitting aperture, said shank of the twist lock assembly lying in the fitting aperture in use and having a diameter equal to the narrowest width of the head whereby the shank will not foul the aperture while coupling and uncoupling the lock head to the load.

2. A twist lock unit according to claim 1 wherein the twist lock element has an axially cut away portion within said body, and a pin disposed in a boring in said axially cut away portion of the element extends parallel to and spaced from the rotational axis of the element, the pin providing a gudgeon pin for engagement by the actuating device, the arrangement being such that longitudinal displacement of the actuating device transversely of the pin will cause the element to rotate in the body to bring at least one portion of the lock head into a position where it engages the under side of the corner fitting aperture to lock the unit thereto.

3. A twist lock unit according to claim 1 wherein said shank comprises a bearing carried by said body, and the element comprises a cylindrical part rotatably mounted in said bearing, said bearing extending down said cylindrical part of the element to said locking head and having an outer diameter equal in cross section to the smallest dimension of the upper part of the head.

4. A twist lock unit according to claim 1 wherein said bearing is split.

5. A twist lock unit according to claim 1 wherein a medial section of the element is cut away to provide axially spaced collars, the medial section being parallel to and spaced from the longitudinal axis of the element, said collars having aligned bores, 21 pin journalled in said bores parallel but offset from the longitudinal axis of the element, and a rod coupled to said pin and extending at right angles thereto and constituting said actuating device whereby longitudinal movement of the rod transversely of the axis of the element will cause the element to rotate through part of a circle about its axis in the body.

6. A twist lock unit according to claim 1 wherein the element preferably at its upper end has a portion of reduced cross section which when rotated engages a contact or one of spaced contacts in an electric circuit with a switch which is actuated by the element in either its locking or unlocking positions.

References Cited UNITED STATES PATENTS 2,972,175 2/1961 Abolins 24221 3,111,895 11/1963 Kraft et al. 24221X 3,456,967 7/1969 Tantlinger et al. 287103X STEPHEN J. NOVOSAD, Primary Examiner 

